An airbag installed in a vehicle is a representative occupant protection device with a seat belt. The airbag system may include a sensing system and an airbag module. The sensing system includes a sensor, a battery, a diagnostic device, and the like and the airbag module includes an airbag and a working gas inflation device. When a collision is detected by the sensor, the working gas inflation device explodes and the airbag rapidly inflates by the exploded gas. A high-pressure gas generated by rapid combustion of a solid or a gas stored in a high-pressure gas container is used in the airbag. The use of airbags has been increased worldwide due to excellent passenger protection performance.
Although attempts have been made to deploy airbags by employing a separate energy storage device even when an element related to an ignition (IGN) power is damaged, performance of the airbags is not satisfactory due to spatial constraint and capacity limitations. Thus, extensive research has been conducted on solving these problems.